Manhole cover



Sept" II, 1928; 1,683,823

. 'J. P. HEIL MANHOLE COVER Filed Dec. 19, 1924 INVEN TOR.

.T 73% 6; TTORNEYS Patented Sept. 11,192 8.

I 1 ,683,823 UNITED STATES PATENT OFFICE.

JULIUS P. HEIL, OF MILWAUKEE, WISCONSIN, .ASSIGNOR TO THE HEIL 60., OF MILWAUKEE, WISCONSIN, A CORPORATION OF ,WISCONSIN.

. MANHOLE COVER.

Application filed December 19, 1924. Serial No. 757,028.

. This invention relates to manhole covers. K

Tanks of many kinds and more particularl'y tanks mounted on motor trucks for carrying oil and gasoline are provided with compartments and each compartment is formedwith a manhole opening closed by a cover which -is usually threaded into the compartment of the tank. The tanks are 10 usually mounted onwooden truck'members and the truck members are supported upon wheels having pneumatic tires so that the tanks are insulated from the ground. Static electricity is ofttimes generated in the tank, [5 and as this is hazardous due to the inflammable fluid carried. in the compartments, it -is customary to attach a short chainat one end to each tank and let the other end drag on the road to ground the tank and prevent K the static electricity from igniting the gaseous vapors rising from the contents of the compartments.

It has been found in practice that the unscrewing and removal of a manhole cover will under certain conditions produce a static spark which is liable to ignite the contents of the tank.

It is one of. the objects of the present invention to-overcome the before mentioned ob- 0 jectionable feature and provide a construction in which this risk will be eliminated.

A further object of the invention is to provide a manhole constructed in a manner to eliminate the possibility of the cover becoming misplaced or lost when disengaged from its compartment.

A further object'of the invention is to provide a manhole cover of simple construction, which is strong and durable and is welladapted for the purpose described.

With the above and other objects in view, the invention consists of the improved 'manhole cover and its parts and combinations as setforth in the claims and all equivalents thereof.

In the accompanying drawing in which the same reference characters indicate the same parts in 'all of the views:

Fig. 1 is a side view of a compartment tank provided with the improved manhole cover;

Fig. 2'is a vertical sectional view of the manhole cover and a portion of the tank taken on a larger scale; and

Fig. 8 is a top view thereof taken on a smaller scale.

improvements in Referring to the drawing, the numeral 5 indicates a tank of the compartment type which is usually mounted on motor trucks.

flange 11 to form a tight closure and also permit the easy with projecting arms 12 to removal of the cover without the use of tools. The cover is also provided with a central threaded opening 13 to receive a closure plug 14.

Immediately beneath the plug opening 13 'the cover is'provided with a' downwardly extending loop or eye 14 to whichis connected one end of a flexible contact member or chain 15. The other end of said contact member or chain is connected to the cap member 7 by an eyed member 15 so that when the cover is unscrewed and removed from the cap the cover will still be grounded to the tank by means of the chain and the liability of the creation of a static spark in separating the cover from the cap or tank will be eliminated. To prevent the turnin of the cover from twisting the chain the sald chain is provided with a turn buckle 16 forming part of the chain and which turn buckle is located immediately below the loop or eye 14. Attention is further directed to the fact that the chain also serves as a means for preventing the cover member from being lost or misplaced when unthreaded from the cap.

It will also be seen that the combination of the cap and cover provides a cover which may be easily removed to permit filling the tank or compartment and when it is desired to clean the tank, the larger cap may be removed.

From the foregoing description it will be seen that the manhole cover is-of very simple construction and is well adapted for the purpose described.

What I claim as my invention is 1. The combination with a metal tank for holding a volatile inflammable fluid and having a threaded opening, of a two-part closure therefor, comprising a metal cap part threaded into said opening and forming an electrical connection with the tank and havin a central threaded opening, a cover part t readed into the cap part opening and having outwardly pro ecting arms for moving said cover part, the removal of the cap part permitting access to the interior of the tank, and a flexible contact member normally Within the tank and connected to the two parts of the closure to form an electrical connection between the two closure parts and to prevent the separation of said parts but permitting the separation of the two-part closure from the'tank.

2. The combination with a metal tank for holding a volatile inflammable fluid and having a threaded opening, of a two-part closure therefor, comprising a metal cap part threaded into said opening and forming an electrical connection with the tank and having a central threaded opening, a cover part threaded into the cap part opening and having a central threaded opening and a loop beneath said opening, the removal of the cap alone permitting access to the interior of the tank, a plug closing said central opening said cover member having outwardly pro ecting arms for movin said cover part, and a metal chain norma ly within the tank and connected at one end to the loop and at its other end to the cap part to form an electrical connection between the two closure parts and to prevent the separation of said parts but permitting the separation of the two part closure from the tank.

In testimony whereof, I afiix my signature.

JULIUS P. HEIL. 

